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Old Sep 06, 2009, 11:26 AM
Needs to do 52 legs !!
jjmouris's Avatar
Verenigd Koninkrijk, Fareham
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Anatomy of a 25 dollar motor



Yup, i just had to do it.

For those who didn't see my posts in the 2008 Avionik thread;
http://www.rcgroups.com/forums/showt...756075&page=25

This is the motor;
http://www.hobbycity.com/hobbycity/s...idproduct=6668

So i de-soldered the controller and picked up the motor from the table. Mmmm..... what is that sound?! Shake shake....... hey there is something loose in here!!!

Well it turns out it was just a blob of balancing material on the rotor.

Here are the guts for your inspection;
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Old Sep 06, 2009, 01:57 PM
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cheap windings

Good photos, Joe. It seems that the winding is a bit slap-dash. Compare with the photo I found, can't find the original, from a Kontronik advert comparing their BL and Fun motors. I think the BL were outsourced?
Wim published pictures showing the construction of such motors. I think the straighter the wires and the more compact the wiring the better.
Maybe the Kira motors are like the Fun which might explain the high efficiency figures Dick as found.
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Old Sep 06, 2009, 02:28 PM
Needs to do 52 legs !!
jjmouris's Avatar
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George,

Nigel said something about a twist in the windings or magnet to get rid of cogging when i asked him why the other motor (Turnigy) was cogging so much. If you look closely you can see there is a bend in the wires at about the middle position. Would this be what Nigel was talking about?

I don't know if this is good or bad. Not enough knowledge about these things hense these pictures so the experts can tell me what's up with this motor.

But i would think this much copper can't be bad for resistance. I guess when you try and squeeze that much in a small space it's not always going to be extremely pritty like those FUN motor's in the picture. Note that i think the Turnigy is more like that, but you will have to open yours up to see.

Actually i am quite impressed that this rotor withstood ~100.000 RPM on the bench and only lost it's magnatism when it reached 110 degrees C in flight.

If i had an RPM sensor i would have been able to do your efficiency calculations but unfortionately i did not. Now i don't know wether to try a 6L version or to stop waisting my money.

Joe
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Old Sep 06, 2009, 02:30 PM
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I was once told that the old BL motors were supplied by hacker. When I took apart a kon BL480 and a hacker B40 they did have extremely similar insides. The colour of the aluminium case was different of course... I recently got an EMAX inrunner motor of 3400 kv which I used in an edf with very good results - it cost around 12 from hong kong and looks similar to the pictures Joe posted, which look simiar to the insides of a kontronik fun500 that I once took apart. If I find the pics I'll post them. I wonder if the turnigy /emax and this motor of Joe's are the same or are there lots of manufacturers?
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Old Sep 06, 2009, 03:00 PM
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Probably all Feigao....
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Old Sep 06, 2009, 03:16 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
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Quote:
Originally Posted by jjmouris
... Nigel said something about a twist in the windings or magnet to get rid of cogging when i asked him why the other motor (Turnigy) was cogging so much. ...
Jos, cogging is a magnetic effect, not an electric effect. Therefore winding position, winding diagram, number of winds, delta<>star etc. does has no effect on cogging.

Quote:
Originally Posted by jjmouris
... If you look closely you can see there is a bend in the wires at about the middle position. Would this be what Nigel was talking about?
I don't know if this is good or bad. Not enough knowledge about these things hense these pictures so the experts can tell me what's up with this motor.
I have seen those 'bends' in Kontronik pictures too. A production method:
http://www.electrifly.com/motors/gpmg5000.html
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Old Sep 06, 2009, 03:33 PM
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I found the old pictures, here is a pic of the windings of a fun500-32:
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Old Sep 06, 2009, 03:33 PM
Needs to do 52 legs !!
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I have taken apart a Faigao before. It didn't have the same quality this motor has. More important the bearings where CRAP on the Faigao. These on the other hand appear to be quite good.

So i wonder if this bend..... or V shape pattern is reducing the efficiency of the motor at all?! Or does it actually help?!

Untill i try a an "L" version i won't know if the overheating was just a function of to much power through to small a motor in to little time with to little cooling or....... the dreaded efficiency!

Note that i have even higher hopes regarding the gold colour Turnigy B36 series motors that they do. It certainly appears to be put together with even greater care. http://www.hobbycity.com/hobbycity/s..._viewItem.asp?
idProduct=6527&Product_Name=Turnigy_B36-56-04_2600kv_Inrunner

Now i wish they would lift the 6S limit on F5B so i could try some of those with HV series controllers.
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Old Sep 06, 2009, 03:36 PM
Needs to do 52 legs !!
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Kyri, i don't see any V bends in there!

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Old Sep 06, 2009, 03:44 PM
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I am not sure if this is a one off? Maybe Dick can tell us what the inside of his 600-42 look like as they may be different / inconsistent? The only reason I had mine apart was to see if there was a problem with the windings, it turned out the rotor was demagged in the end. But then the fun 500 rotor is so small there is not much mass there at all. Bigger (longer) rotors have got to be better for a resitance to demagging potential.
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Old Sep 06, 2009, 03:46 PM
Grow old disgracefully!
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Quote:
Originally Posted by jjmouris
I have taken apart a Faigao before. It didn't have the same quality this motor has. More important the bearings where CRAP on the Faigao. ....
I second that. I use Feigao motors in my RC combat models and they are good motors - at least they are now that I have replaced the bearings and pinned pinned the ends of the cans in place to stop them falling off .

Dick
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Old Sep 06, 2009, 03:53 PM
Needs to do 52 legs !!
jjmouris's Avatar
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Dick, i bet you didn't try those at 5KW!

Note even the entry power was well above 3KW on the 6S pack.

Joe, who is entrinsically crazy.
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Old Sep 06, 2009, 03:54 PM
Grow old disgracefully!
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Quote:
Originally Posted by Kyri
I am not sure if this is a one off? Maybe Dick can tell us what the inside of his 600-42 look like as they may be different / inconsistent?.....
After several years of trusty service my poor old 600-42 went back to Kontronik with a fault - followed a few days later by my new Kira 600-38 after a crash .

If Kontronic send the old bits back with the new motors I will have a look and take some pictures.

(motorless) Dick
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Old Sep 06, 2009, 04:03 PM
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Getting motors apart

I can't get mine apart. Michel Uzan can do it and I have asked him how. But I have tried the Turnigy gold using Joe's method of hitting it with a hammer, and far from Dick's endbells which fall off these are well stuck on! All I have done is increase the end play on the motor shaft!

I have also tried to get a Hacker FAI apart with no luck. I heated the end of the motor with a high temperature gun and wiggled and pulled with the gearbox outer in a vice, no joy. I did not try the hammer technique.

Any ideas?
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Old Sep 06, 2009, 04:12 PM
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George when I tried to take my fun motor apart, I made a steel bar (6" long and drilled to the mounting of the g/b) and put rubber bands round the motor. Using a leather glove and giving a good twist, the glue bond between the front endbell and front plate was weaker than the bond between g/b and g/b adaptor. So I inadvertently got it apart. Once the front was off and rotor out, I used a wooden dowel to push out the back plate. Did not want to risk the bond between the rotor magnet and shaft by hitting the shaft and using the rotor to push off the endbell - don't ask me how I know that

Heat might be counter intuitive since the alu will expand relative to the carbon. Maybe try cooling the alu and usnig a stanley blade to open up the gap and get the end off by working your way round the motor circumference and maybe gently tapping the rotor.
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